The invention refers to a sensor for the determination of the incidence angle of radiation, in the following designated as ‘sensor’, as well as a corresponding method for the determination of the incidence angle of a radiation source.
The determination of the position of radiation sources, in particular the position of the sun, in azimuth as well as in the elevation angle is an always persisting task, for whose realization various devices were used in the past and still in the present, which made use of either different transmissivity of materials for the radiation, or diffraction or refraction of the radiation to be measured in optically active materials, or a combination of these.
For the purpose of using the position data of radiation sources in a technical manner, devices and methods are required, that offer an appropriate precision of measurement as well as a simple and automatic processability of identified data. Areas of application for the technical utilization are, e.g. the automobile industry or building services engineering.
Most of the to-this-date technically used devices for this purpose comprise three main components: a photo sensitive surface for a spatially resolved detection of the radiation, a device for the modification of the incident radiation, and a unit for pre-processing the data.
Devices according to the state of the art offer no fully integrated solutions, but consist of separate parts.
Following the realization of the photo sensitive surface in older solutions through the arrangement of separate, and possibly spatially distributed photo elements, solutions with photo sensitive surfaces consisting of sensor arrays prevail subsequently, i.e. through a regular arrangement of light sensitive component, through which the incidence angle of the radiation is determined by determining whether a current is induced by photons or not. The WO 94/17427 describes such a sensor array, in which however the single cells only deliver digital responses. Thus, the resolution of these sensors is determined through the distance of the single cells within the sensor array. Using respective optical means such as converging lenses, the resolution is slightly improved; in addition, the use of a CCD image sensor is proposed. The use of separate optical auxiliary means such as lenses; however, do not allow one to design the sensor in a compact manner.
Additionally with using arrangements of photo sensitive cells, it is not beneficial if the cells are read out digitally. A higher resolution can be obtained if one can read out and evaluate the photo currents generated in the photo sensitive cells in an analogue way. Because of a small amount of currents, relatively bigger surfaces are however required for a detection of analogue data or for using the photo cell arrays to reduce the interference susceptibility of the measurement.
In the known systems, such a sensor has a complex design, and requires a bigger surface as well as an extensive evaluation.